Everpure EV9607-04 7SO Softening Cartridge Reduces minerals such as calcium and magnesium May be used on water having up to 30 grains hardness per-Gallon (500 mg/L) at flow rates of up to 1/2-Gallon per minute Fits all existing Everpure heads. Recommended use as second cartridge in QC Twin Series configuration head (EV9272-24) Sanitary cartridge replacement is simple, quick and clean. Internal filter parts are never exposed to handling or contamination